With a proportion of almost 60 % by weight of the accessible structure of the earth’s crust, feldspars are by far the most frequent group of minerals. Feldspar is a chemically resistant tectosilicate with a thick-slated grain morphology. HPF offers potash as well as sodium feldspars which are processed and separated by an elaborate screening technique, then classified and micro-ground.

Nepheline syenite: a silica-free mineral

Nepheline syenite consists of feldspars and feldspar-type minerals such as albite, microcline and nepheline. This mineral raw material contains no crystalline silica. Exactly as feldspar, nepheline syenite is inert and is characterized by a Mohs hardness of 6, and a high degree of whiteness. HPF only offers surface-treated types.